Spotting rifle ignition for larger caliber gun



July 16, 1963 1-. STEVENSON 3,097,564

' SP OTTING RIFLE IGNITION FOR LARGER CALIBER GUN Filed July 21, 1961 INVENTOR. THOMAS STEVENSON J} flaw; a. J, @u z M. W

ATTORNEY Unite j grates 3,@97,5fil Patented July 16, 1963 hire Filed July 21, 1961, er. N 125,381 2 Claims. (Cl. 89ll.'7) (Granted under Title 35, U.S. Code (1952 sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me or any royalty thereon.

This invention relates to means for firing the larger caliber gun of a spotting rifle combination and has for an object to simplify the firing apparatus for that larger gun in order that it may be fired by the spotting rifle.

A prior patent 2,981,151 dated April 25, 1961, for lgnition System for Caseless Rounds in Open Breech Type Guns disclosed the use of a blank cartridge for firing such a gun from the outside of it in order to eliminate the disadvantages of the previously used apparatus for firing such guns.

According to this invention it has been discovered that the barrel of the usual spotting rifle may be close enough to the propellant chamber of the larger gun on which the spotting rifle is mounted for the propellant in the larger gun to be ignited by the propellant flame from the spotting gun. For this purpose an enclosed passageway has a diameter of about 75 to about 50% of the bore of the spotting rifle barrel and extends from the front end of the spotting cartridge case into the propellant chamber of the larger gun. In order that the spotting rifle may be fired without firing the larger gun a valve closes said passageway against the admission of any flame into the propellant in the large gun in advance of it being ready to fire but such valve is opened in response to a trigger pull and held open while the spotting rifle is being fired atter getting on the target.

Referring to the drawing, the single figure shows the present invention embodied in a spotting rifle combination with a larger gun.

A usual 50 caliber spotting rifle It is aifixed to a larger caliber 90 millimeter open breech type recoilless rifle 11 utilizing caseless propellant for a fin stabilized projectile. The central open breech 12 is provided with an expansible venturi nozzle 13 capable of holding the ammunition in place when the muzzle is elevated. Instead of this type venturi, a bar type breech closure having a venturi opening on each side of it may be also used. Within the larger gun 11 is shown a fin stabilized round of ammunition which includes a projectile body portion 14, and stabilizing fins 15 mounted from the boom 16. Around the boom are disc type sections of propellant 17. A rotating band 18 initiates a low rotation rate for the projectile of between about 10 to 20 revolutions per second on cooperation with the lands and grooves in the gun barrel. The cartridge case 19 is preferably of the consumable type that offers minimum resistance to a flame from the spotting rifle being admitted for ignition of propellant 17. Black powder 24) or other priming mixture is shown around the boom 16 within the propellant discs 17, between some or all of the discs and radially through the cartridge case where the flame from the spotting rifle impinges.

The spottin rifle barrel 21 is provided with a front support 22 and a rear support constituted by a connector 23 threaded into the spotting rifle and large gun as shown. Extending through connector 23 is a flash hole 24 of about of an inch in diameter for the /2 inch or 50 caliber bore. To close hole 24 against the admission of flame to the large gun during the firing of the spotting rifle while striving to get on a target, a valve 25 of the sliding type closes hole 24. A spring 26 cooperates with a head 2'7 on an extension of the slide valve 25 and with the connector 23 to bias the valve to its closed position with the flash hole closed against the admission of flame to the propellant 1'7 and 2%. On pulling linkage 28' the valve 25 is moved to the left until the hole through it is brought into axial alinement with the flash hole 24. On later firing the spotting rifle cartridge its flame after pressure starts the projectile 29 outwardly, is enabled to travel through hole 24 igniting the cartridge case 19 and priming material 20 for igniting propellant l7 and firing projectile 14. The metal 50 caliber cartridge case 30 contains the usual propellant for the projectile 29. While getting onto a target with valve 25 closed the mission of propellant in cartridge case 3% is to start projectiles 29 with a uniform velocity.

When a spotting projectile had hit the target and it is desired to fire the large gun, a rear trigger 31 on the spotter may pull valve 25" to the left to its open position and hold this valve open while pulling a second or forward trigger 32 for firing the spotter. At this time there is no need to hope for projectile 29 to get on the target again under reduced pressure but it is only necessary for the spotter propellant to be able to push projectile out of the spotter barrel to be ready for firing another spotting shot later. Whether or not the smaller projectile falls short in firing the larger gun should be of no importance but it is necessary that the flame be able to pass through flash hole 24- and ignite the propellant of the larger gun. As soon as propellant in cartridge 34 causes projectile 29 to clear the flash hole 24, then the igneous gases are enabled to penetrate to fire propellant 17. The diameter of the hole 24.- should not be larger than the spotter bore. If this hole 24 is too small it will fail to get enough heat and pressure to the large gun propellant. In practice a hole of an inch or 75% of the diameter of the spotter bore /z inch) was found suitable.

Any of a number of well known types of trigger mechanisms may be used. For example two triggers on the spotter will enable one of them to pull linkage 28 for opening valve 25 and hold it open while firing spotting rifle 10 for firing the large gun. On release of both triggers the spring 26 closes valve 25 for refirin-g of the spotting rifle in its usual mission of striving to get on the target. A stop 33 limits movement of the valve 25 to insure the hole in the valve being in alinement with the hole 24 in the connector.

In practice the spotting rifle will have a magazine, not illustrated, because projecting on the far side of the smaller gun to enable this smaller gun to be mounted closer to the larger gun than if the usual magazine were placed below the smaller gun and between it and the larger gun. With the magazine so placed the triggers 31 and 32 may also be on the far side close to the magazine, but for simplicity in disclosure these triggers are shown between the guns.

Among the advantages of this invention may be mentioned the fact that the flame and hot gases from a standard caliber spotting round possess enough energy in the portion coming through the side orifice to pierce substantially instantaneously the plastic envelopes used for containing the major caliber propellant. In other words this flame does not have to be gradually burned through such an envelope but has suflicient explosive force to blast through the envelope. Another advantage is the elimination of the need for carrying and using special cartridges for firing the larger gun, which cartridges are in addition to the spotter cartridges as was contemplated in said prior Patent 2,981,151 dated April 25, 1961 mentioned above which eliminated the need for rear end connections to the major caliber round having to be made in combat under all weather conditions.

The term caseless round has its usual significance and includes not only those rounds having no case but also those having a case which does not have to be extracted from a gun barrel but has been disposed of by combustion or by being frangible.

I claim:

1. In a combination of a recoilless weapon with a spotting rifle secured thereto and of substantially smaller caliber than said weapon, each of said weapon and spotting rifle having a chamber in which a projectile is adapted to be located for firing, and each of said spotting rifle and weapon having a propellant chamber in rear of said projectile chamber, the combination therewith of the improvement for rendering a service round in said spotting rifle capable of firing a propellant in said Weapon, said improvement including a short direct enclosed flame passageway leading from adjacent a propellant chamber in said spotting rifle into a propellant chamber in said weapon and generally radially through a side wall of said Weapon propellant chamber for igniting a caseless propellant when in said weapon from an ignited round of propellant in said spotting rifle, said passageway having a diameter of between about 50% to 75% of the spotting rifle bore, and a valve by which said passageway may be opened or closed to allow or prevent the passage of an igniting flame to said weapon, said spotting rifle being provided with a trigger means by which it is fired and a connection between said valve means and at least a portion of said trigger means whereby said valve means may be controlled by said trigger means to which connected.

2. A combination according to claim 1 in which said valve means is slidable, a spring controls movement of said valve means in one direction, and said trigger means includes two triggers, one by which said spotting rifle may be fired while said passageway is closed and the other by which said valve means is moved to open said passageway and fire said weapon on firing said spotting rifle.

References Cited in the file of this patent UNITED STATES PATENTS 1,309,791 Aasen July 15, 1919 1,376,320 Crowe Apr. 26, 1921 1,622,160 Mattlet Mar. 22, 1927 2,396,896 Smith Mar. 19, 1946 2,805,603 Musser Sept. 10, 1957 2,981,151 Stevenson Apr. 25, 196-1 

1. IN A COMBINATION OF A RECOILLESS WEAPON WITH A SPOTTING RIFLE SECURED THERETO AND OF SUBSTANTIALLY SMALLER CALIBER THAN SAID WEAPON, EACH OF SAID WEAPON AND SPOTTING RIFLE HAVING A CHAMBER IN WHICH A PROJECTILE IS ADAPTED TO BE LOCATED FOR FIRING, AND EACH OF SAID SPOTTING RIFLE AND WEAPON HAVING A PROPELLANT CHAMBER IN REAR OF SAID PROJECTILE CHAMBER, THE COMBINATION THEREWEITH OF THE IMPROVEMENT FOR RENDERING A SERVICE ROUND IN SAID SPOTTING RIFLE CAPABLE OF FIRING A PROPELLANT IN SAID WEAPON, SAID IMPROVEMENT INCLUDING A SHORT DIRECT ENCLOSED FLAME PASSAGEWAY LEADING FROM ADJACENT A PROPELLANT CHAMBER IN SAID SPOTTING RIFLE INTO A PROPELLANT CHAMBER IN SAID WEAPON AND GENERALLY RADIALLY THROUGH A SIDE WALL OF SAID WEAPON PROPELLANT CHAMBER FOR IGNITING A CASELESS PROPELLANT WHEN IN SAID WEAPON FROM AN IGNITED ROUND OF PROPELLANT IN SAID SPOTTING RIFLE, SAID PASSAGEWAY HAVING A DIAMETER OF BETWEEN ABOUT 50% TO 75% OF THE SPOTTING RIFLE BORE, AND A VALVE BY WHICH SAID PASSAGEWAY MAY BE OPENED OR CLOSED TO ALLOW OR PREVENT THE PASSAGE OF AN IGNITNG FLAME TO SAID WEAPON, SAID SPOTTING RIFLE BEING PROVIDED WITH A TRIGGER MEANS BY WHICH IT IS FIRED AND A CONNECTION BETWEEN SAID VALVE MEANS AND AT LEAST A PORTION OF SAID TRIGGER MEANS WHEREBY SAID VALVE MEANS MAY BE CONTROLLED BY SAID TRIGGER MEANS TO WHICH CONNECTED. 